FIG. 1 shows a schematic representation of a tiled display.
The display tiles T can be an emissive display apparatus like e.g. a Liquid Crystal Display apparatus or it can be a rear projection display apparatus.
FIG. 1 also shows schematically how the picture elements or pixels P are arranged on the display tile T. Three sub-pixels green, red and blue lie close to one another and produce in their totality a picture element of the image displayed. The picture elements follow one another with a spacing A. The broken line indicates the inner area of the display tile T on which an image can be formed and viewed by a viewer. The space between the broken line and the edges of a display tile T is a non-display area. The non-display area often corresponds to a space occupied by a bezel B whose primary function is to hold the LCD panel of the LCD in position. In the prior art the spacing between two adjacent picture elements P displayed onto adjacent display tiles T is largely determined by the distance separating two adjacent display tiles T and the width of the bezel B. The space between the display areas of two adjacent display tiles is often referred to as the seam (SEAM). The minimum distance between two adjacent display tiles T depends on the clearance needed to allow thermal and humidity expansion of the display tiles T without misalignment, bowing or damaging of the Liquid Crystal panel (or projection screen) of the display tile T.
The problem of thermal and humidity expansion and the relative movement of tiles with respect to each other and its impact on the inter-tile seams is well known in the art too.
The width of the bezel can be decreased or the bezel can be eliminated as e.g. proposed in U.S. Pat. No. 8,446,540 “Display device having an enlarged display area”.
The problem is that the solution may not be reliable for large liquid crystal panels (e.g. with more than one meter of diagonal) as the weight of the panel could overcome the forces exerted by the “fixing member” and “panel guide portion”.
Another problem is that the panel guide portion may not be in metal to avoid scratching the liquid crystal panel. Therefore, it needs to be thick enough to withstand the forces applied on it. The seam will thus be at least twice as wide as the panel guide portion will be thick.
The author of U.S. Pat. No. 8,446,540 also excludes the use of adhesive tape to fasten the liquid crystal panel to a frame because it is incompatible with reliability and durability of the assembly.
The reliability and durability could be improved if the adhesive tape were thick enough.
For instance, with values of α-aluminum=23.8·10−6 1/K and α-glass=8.1·10−6 1/K (α being the coefficient of thermal expansion) and a total bond length at room temperature of L0=1500 mm for a change in temperature of ΔT=40 K a difference in length at both ends of ΔL=ΔT·L0/2·(α-Al−α-Glass)=0,471 mm will occur in a stress-free assembly (i.e. when aluminum and metal are not bonded together). A pressure sensitive mounting tape with a thickness of 0.8 mm should be suitable to compensate Δα-induced stress in this configuration.
But such a thickness of pressure sensitive mounting tape is not compatible with a seam of less than 1 mm.
The art also does not provide solutions for reliably fastening a liquid crystal panel affected by tolerances (e.g. a mismatch between the lateral dimensions of the glass panel delimiting the liquid crystal layer) while at the same time avoiding the use of a bezel or rim.
There is a need to improve the art.